Inactivation of Numb and Numblike in embryonic dorsal forebrain impairs neurogenesis and disrupts cortical morphogenesis

Neuron. 2003 Dec 18;40(6):1105-18. doi: 10.1016/s0896-6273(03)00755-4.


Numb and Numblike, conserved homologs of Drosophila Numb, have been implicated in cortical neurogenesis; however, analysis of their involvement in later stages of cortical development has been hampered by early lethality of double mutants in previous studies. Using Emx1(IREScre) to induce more restricted inactivation of Numb in the dorsal forebrain of numblike null mice beginning at E9.5, we have generated viable double mutants that displayed striking brain defects. It was thus possible to examine neurogenesis during the later peak phase (E12.5-E16.5). Loss of Numb and Numblike in dorsal forebrain resulted in neural progenitor hyperproliferation, delayed cell cycle exit, impaired neuronal differentiation, and concomitant defects in cortical morphogenesis. These findings reveal novel and essential function of Numb and Numblike during the peak period of cortical neurogenesis. Further, these double mutant mice provide an unprecedented viable animal model for severe brain malformations due to defects in neural progenitor cells.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Cycle / genetics
  • Cell Cycle / physiology
  • Cell Differentiation / genetics
  • Cell Differentiation / physiology
  • Cell Division / genetics
  • Cell Division / physiology
  • Cerebral Cortex / cytology
  • Cerebral Cortex / embryology
  • Cerebral Cortex / growth & development
  • Cerebral Cortex / metabolism
  • Female
  • Gene Silencing*
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / deficiency*
  • Membrane Proteins / genetics*
  • Mice
  • Mice, Transgenic
  • Nerve Tissue Proteins / biosynthesis
  • Nerve Tissue Proteins / deficiency*
  • Nerve Tissue Proteins / genetics*
  • Pregnancy
  • Prosencephalon / cytology
  • Prosencephalon / embryology*
  • Prosencephalon / growth & development
  • Prosencephalon / metabolism*


  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Numb protein, mouse
  • Numbl protein, mouse